In Search of Mesenchymal Stem Cells: Bone Marrow, Cord Blood, or Peripheral Blood

Mesenchymal stem cells (MSC) are capable of self-renewal and differentiation into various connective tissue lineages. Therefore, they have attracted a lot of attention from investigators in the context of stem cell therapies. In our study, we have evaluated the frequency, phenotype and differen tiation potential of MSC in bone marrow (BM) cord blood (CB) and mobilized peripheral blood (mPB). Sixteen CB, 11 BM and 19 mPB were obtained from normal donors. Mononuclear cells sus pended in culture medium and seeded in culture flasks. Flasks were incubated in a CO2 incubator with a change of culture medium every 4 days and passaged when fibroblast like cells reached confluence. For every other passage, MSC were examined for CD13, CD44,CD34 by flow cytometry and induced to differentiate into adipocytes and osteocytes. All BM samples produced MSC that survived multiple passages in mesenchymal culture me dium over 4 months. CB and mPB samples produced a non-confluent adherent layer of heterogeneous cells, and did not proliferate beyond the first passage. Immunophenotype of BM-derived MSC in every other passage were CD34-, CD13+ and CD44+, the adipogenic and osteogenic differentiation were con firmed by Oil-red O and Von Kossas staining, respectively.The mentioned evaluation for mPB and CB were not attempted because these were not confluent even in the first passage. In our study, only human BM cells produced MSC. These cells are positive for MSC sur face proteins and differentiate into MSC lineages.